Is there a Youtube API that gives only audio? [closed]

I've searched for this question several times

Many suggested that 'Get both audio and video. And hide video.' and said that 'there is no audio only API'

But it needs more traffic than when only audio is retrieved if I wanted to listen to music via Youtube.

What makes me confused is, an android app called Firetube provides audio only.

Is this just a trick or does Google provides AUDIO ONLY API?

YES YOU CAN

Yes, it is certainly possible, here is an API for that:

https://market.mashape.com/ehmo/savedeo

While it is against YouTube Terms of Service, it is technically possible to hack your way to the audio-only download link, and that's how the API's above work.

The is how I imagine the SaveDeo API does its magic: Download ONLY audio from a youtube video

This is what the guy at SaveDeo told me:

Youtube has audio only files. Savedeo doesn't do anything beyond providing you with the link. How we're doing this is the reason why are you using savedeo, isn't it.

Regarding the Terms of Service of the YouTube API

https://developers.google.com/youtube/terms/developer-policies

YOU CAN'T :

separate, isolate, or modify the audio or video components of any YouTube audiovisual content made available through the YouTube API;

promote separately the audio or video components of any YouTube audiovisual content made available through the YouTube API;

youtube-dl

This is technically possible and very easy to do with youtube-dl. Note: this isn't an "api". This isn't supported by Google, and it technically may be against there TOS. I assume if you have access in North Korea, that it's totally legal.

# Download the stream and extract the audio.
youtube-dl -x

# If you just need the url you can use
youtube-dl -x --get-url <URL>